Mineral, Specifically A Rock Fragment

Rounded gray pebble, likely fine-grained metamorphic rock

Possibly quartz-rich gneiss or granofels; exact identification requires closer examination

Sandstone Pebble

Sedimentary quartz arenite

Banded Greywacke

Greywacke (Lithic wacke)

Quartz-bearing rock, possibly pegmatite

Likely quartz and feldspar with dark mica or other accessory minerals; exact rock type is uncertain from the image

Banded Agate / Lace Agate

Agate (Silica/Quartz) - SiO2

Chert (specifically Banded Chert or Flint)

Microcrystalline Quartz (SiO2)

Quartz-rich gravel fragment

Quartz (silicon dioxide, SiO₂), possibly with feldspar or carbonate inclusions

Sandstone (Tumbled / Rounded)

Sedimentary Rock (Quartz arenite)

Limestone (specifically Travertine or Tufa)

Calcium Carbonate (CaCO3)

Sandstone (Lithic Wacke)

Clastic sedimentary rock (primarily SiO2 with rock fragments)

Small weathered mineral/rock fragment

Indeterminate; possibly quartz-bearing feldspathic rock or calcite-rich specimen

Quartz-bearing iron-stained breccia

Brecciated quartz/quartzite with iron oxides, chiefly SiO₂ with hematite/goethite and possible feldspar or host-rock fragments

Ocean Jasper

Spherulitic Chalcedony (SiO2)

Weathered fossil shell or crinoid fragment

Likely fossilized echinoderm or bivalve fragment; exact taxon indeterminate from the image

Rounded gray-green beach cobble

Unidentified lithic cobble; exact rock type cannot be determined from the image

Quartz crystal fragment

Quartz (SiO₂), likely a small clear-to-gray crystal fragment

Conglomerate

Conglomerate (clastic sedimentary rock)

Granite

Granite; primarily quartz, feldspar, and mica

Quartz (specifically Clear Quartz or Rock Crystal)

Silicon Dioxide (SiO2)

Boxwork Siderite or Sepatarian Nodule Weathering

Siderite (FeCO3) with secondary mineralization or Boxwork Geode fragment

Rounded greenish-gold rock or mineral pebble

Indeterminate; possibly serpentine-rich stone, weathered sulfide, or iron-stained metamorphic rock

Rough Garnet in Matrix

Almandine Garnet (Fe3Al2Si3O12)

Quartz Geode Fragment

Silicon Dioxide (SiO2)

Weathered granite fragment

Granite, predominantly quartz–feldspar–mica rock

Small water-worn pebble, likely quartz-rich

Rock fragment of uncertain composition; possibly quartzite or chert

Puddingstone (specifically Michigan/Gowganda Puddingstone)

Conglomerate (Jasper Conglomerate)

Quartz Pebble

Silicon Dioxide (SiO2)

Porphyry (specifically Porphyritic Andesite / Rhyolite)

Porphyritic Igneous Rock

Likely garnet-bearing rock fragment

Garnet-bearing schist or gneiss; garnet is commonly almandine, Fe₃Al₂(SiO₄)₃

Chert (specifically Tan/Yellow Chert)

Silicon Dioxide (SiO2)

Sandstone with Manganese Staining

Quartz Arenite / Sedimentary Rock

Red Sandstone

Sedimentary Quartz Arenite / Arkose

Uncertain pale green-gray mineral/rock fragment

Possibly serpentine-bearing rock or greenstone; exact identification requires testing

Concretion

Sedimentary Concretion (Ironstone / Calcite Concretion)

Ironstone / iron-oxide-rich rock fragment

Likely limonite/goethite-rich ironstone; exact identification is not possible from the image alone

Sandstone

Clastic Sedimentary Rock

Sandstone Concretion

Ferruginous Sandstone Concretion

Likely potassium feldspar (orthoclase) fragment

Orthoclase, KAlSi₃O₈ (tentative identification)

Sandstone (with Iron Staining)

Clastic sedimentary rock (SiO2 with Fe2O3 oxides)

Sandstone

Arenite (SiO2 primarily)

Dalmatian Stone

Dalmatian Jasper (Aphanitic Igneous Rock with Arfvedsonite inclusions)

Likely weathered quartz-bearing rock fragment

Indeterminate; appears to contain quartz (SiO₂) with iron-oxide staining, possibly from quartzite, granite, or pegmatite